C# OpenId Connect Dicovery Helper

OpenIdConnectHelper.cs

using System.Collections.Concurrent;

namespace Gbt.Identity.RavenDb.OpenId;

public class OpenIdConnectHelper(string Issuer)
{
  private static readonly ConcurrentDictionary<string, OpenIdConfiguration> Cache = new();

  public record OpenIdConfiguration(string authorization_endpoint, string token_endpoint);

  public async Task<OpenIdConfiguration> Discover(CancellationToken cancellationToken = default)
  {
    if (Cache.TryGetValue(Issuer, out var cachedConfig))
      return cachedConfig;

    var httpClient = new HttpClient();
    var oidcDiscovery = new UriBuilder(Issuer);
    oidcDiscovery.Path = "/.well-known/openid-configuration";
    var response = await httpClient.GetAsync(oidcDiscovery.Uri, cancellationToken);
    var config = await response.Content.ReadFromJsonAsync<OpenIdConfiguration>(cancellationToken: cancellationToken);

    if (Cache.TryAdd(Issuer, config))
      _ = Task.Delay(TimeSpan.FromMinutes(10)).ContinueWith(_ => Cache.Remove(Issuer, out var _));

    return config;
  }
}